1. Field of the Invention
The present invention relates to a zoom lens used in an electronic camera, such as a digital camera, a video camera, a camera for broadcasting, a camera for movies and a camera for surveillance, and also to an imaging apparatus on which the zoom lens is mounted.
2. Description of the Related Art
In electronic cameras, such as a camera for broadcasting and a camera for film-making, a fluctuation of an angle of view caused by focusing is not desirable. Therefore, as a zoom lens consisting of four lens groups of a first through fourth lens groups, a zoom lens in which the first lens group is divided into an 11th lens group having negative refractive power, a 12th lens group having positive refractive power and a 13th lens group having positive refractive power, and the 12th lens group is moved during focusing has been proposed (please refer to Japanese Unexamined Patent Publication No. 9(1997)-015501 (Patent Document 1) and Japanese Unexamined Patent Publication No. 10(1998)-062686 (Patent Document 2)). Further, as a zoom lens used in such an electronic camera, a zoom lens consisting of five groups has been proposed to increase the magnification ratio of the zoom lens (please refer to Japanese Unexamined Patent Publication No. 10(1998)-031157 (Patent Document 3)). Especially, in a camera for movies, a lens needs to have performance similar to an imaging lens for an HDTV (high definition television) camera or higher. As a lens satisfying such a need, for example, a lens disclosed in Japanese Unexamined Patent Publication No. 2004-341238 (Patent Document 4) has been proposed.